feat(admin): sprint 19 admin dashboard, routing, i18n

- Add admin dashboard feature (models/gateway/facade/components/page)
- Wire admin/products routes and backoffice coming-soon placeholders
- Add lastPublishedAt to ProjectEditorFacade/state
- Add dashboard i18n keys (en/ru/hy) and docs/ADMIN.md

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/features/backoffice/shared/backoffice-coming-soon-page.component.html

@@ -0,0 +1,5 @@
+<div class="coming-soon">
+  <h1 class="coming-soon__title">{{ titleKey | translate }}</h1>
+  <p class="coming-soon__description">{{ 'dashboard.comingSoonDescription' | translate }}</p>
+  <a class="coming-soon__link" [routerLink]="['../dashboard']">{{ 'dashboard.backToDashboard' | translate }}</a>
+</div>

src/app/features/backoffice/shared/backoffice-coming-soon-page.component.scss

@@ -0,0 +1,32 @@
+.coming-soon {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-start;
+  gap: 12px;
+  max-width: 640px;
+  margin: 40px auto;
+  padding: 24px;
+  text-align: left;
+}
+
+.coming-soon__title {
+  margin: 0;
+  font-size: 24px;
+  font-weight: 800;
+  color: var(--text-primary, #1e3c38);
+}
+
+.coming-soon__description {
+  margin: 0;
+  color: var(--text-secondary, #667a77);
+}
+
+.coming-soon__link {
+  color: var(--primary-color, #497671);
+  font-weight: 600;
+  text-decoration: none;
+}
+
+.coming-soon__link:hover {
+  text-decoration: underline;
+}

src/app/features/backoffice/shared/backoffice-coming-soon-page.component.ts

@@ -0,0 +1,19 @@
+import { ChangeDetectionStrategy, Component, inject } from '@angular/core';
+import { CommonModule } from '@angular/common';
+import { ActivatedRoute, RouterLink } from '@angular/router';
+import { TranslatePipe } from '../../../i18n/translate.pipe';
+
+/** Landing page for backoffice sections not built yet (categories, static pages, transactions, orders, media). Route `data.titleKey` sets the section name; falls back to the generic "coming soon" title. */
+@Component({
+  selector: 'app-backoffice-coming-soon-page',
+  standalone: true,
+  imports: [CommonModule, RouterLink, TranslatePipe],
+  templateUrl: './backoffice-coming-soon-page.component.html',
+  styleUrls: ['./backoffice-coming-soon-page.component.scss'],
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+export class BackofficeComingSoonPageComponent {
+  private readonly route = inject(ActivatedRoute);
+
+  readonly titleKey: string = this.route.snapshot.data['titleKey'] ?? 'dashboard.comingSoonTitle';
+}